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To rename a collection in MongoDB, you can use the renameCollection() method. This method allows you to change the name of an existing collection to a new name within the same database. Syntax db.oldCollectionName.renameCollection('newCollectionName'); Sample Data Let us first list all the collections from database sample to see the available collections ? use sample; show collections; copyThisCollectionToSampleDatabaseDemo deleteDocuments deleteDocumentsDemo employee informationAboutDelete internalArraySizeDemo prettyDemo selectWhereInDemo sourceCollection updateInformation userInformation Example Now let's change collection name 'informationAboutDelete' to 'deleteSomeInformation' ? db.informationAboutDelete.renameCollection('deleteSomeInformation'); { "ok" : ... Read More
To check the current number of connections to MongoDB, you can use the db.serverStatus().connections command. This returns detailed connection statistics including current, available, and total connections created. Syntax db.serverStatus().connections; Alternative syntax using a variable ? var connectionInfo = db.serverStatus(); connectionInfo.connections; Method 1: Direct Command The simplest way to check connection statistics ? db.serverStatus().connections; { "current" : 1, "available" : 999999, "totalCreated" : 1 } Method 2: Using a Variable Store the server status and access connection data ? var checkCurrentNumberOfConnections ... Read More
You can use the $ne (not equal) operator to query for boolean fields that are "not true". This operator returns documents where the field value is either false or does not exist. Syntax db.collectionName.find({ fieldName: { $ne: true } }); Sample Data Let us create a collection with employee documents to demonstrate the query ? db.queryForBooleanFieldsDemo.insertMany([ { "EmployeeName": "Larry", "EmployeeAge": 24, "isOldEmployee": true }, { "EmployeeName": "Mike", "EmployeeAge": 20, "isOldEmployee": false }, { "EmployeeName": "Sam", "EmployeeAge": ... Read More
To select records having a given key, you can use the $exists operator. This operator checks whether a field exists in the document, regardless of its value. Syntax db.collectionName.find({ fieldName: { $exists: true } }); Sample Data Let's create a collection with sample documents to demonstrate the $exists operator ? db.selectRecordsHavingKeyDemo.insertMany([ {"StudentName": "John", "StudentAge": 21, "StudentMathMarks": 78}, {"StudentName": "Carol", "StudentMathMarks": 89}, {"StudentName": "Sam", "StudentAge": 26, "StudentMathMarks": 89}, {"StudentName": "Sam", "StudentMathMarks": 98} ]); { ... Read More
The command to show the database currently used in MongoDB is the following − Syntax db; This command returns the name of the currently active database in your MongoDB session. Check Available Databases Let us first check how many databases are present. The query is as follows − show dbs; The following is the output displaying all the databases − admin 0.000GB config 0.000GB local 0.000GB sample 0.000GB sampleDemo 0.000GB studentSearch 0.000GB test 0.003GB Example 1: Check Current Database Now, we have the list ... Read More
To clear the console in MongoDB shell, you can use either a keyboard shortcut or the cls command. Both methods instantly clear the terminal display, giving you a clean workspace. Syntax Method 1: Keyboard Shortcut Ctrl + L Method 2: Command cls Method 1: Using Ctrl + L (Recommended) The fastest way to clear the MongoDB console is using the keyboard shortcut. Simply press Ctrl + L while in the MongoDB shell ? > use myDatabase ... Read More
You can use $pull operator to remove objects from an array in MongoDB. The $pull operator removes all array elements that match a specified query condition. Syntax db.collection.update( { "matchField": "value" }, { $pull: { "arrayField": { "field": "value" } } } ); Sample Data Let us create a collection with a document containing an array of objects ? db.removeObjectFromArrayDemo.insertOne({ "StudentName": "John", "StudentAcademicProjectDetails": [ { ... Read More
MongoDB automatically indexes every value within an array field when you create an index on that field. This allows efficient querying of individual array elements without scanning the entire collection. Syntax db.collection.createIndex({"arrayField": 1}); db.collection.find({"arrayField": "specificValue"}); Sample Data Let us create a collection with a document containing an array field ? db.indexingForArrayElementDemo.insertOne({ "StudentFavouriteSubject": ["MongoDB", "MySQL"] }); { "acknowledged": true, "insertedId": ObjectId("5c8acdca6cea1f28b7aa0816") } Display the document to verify ? db.indexingForArrayElementDemo.find().pretty(); { ... Read More
Yes, MongoDB aggregation framework supports the $or operator within the $match stage to match documents that satisfy at least one of multiple conditions. This allows you to create flexible filtering logic in your aggregation pipelines. Syntax db.collection.aggregate([ { $match: { $or: [ { field1: value1 }, ... Read More
To query documents by comparing two fields in MongoDB, you can use the $where operator with JavaScript expressions or the more efficient $expr operator with aggregation expressions. Syntax // Using $where (JavaScript) db.collection.find({ $where: function() { return this.field1 < this.field2; } }); // Using $expr (Recommended) db.collection.find({ $expr: { $lt: ["$field1", "$field2"] } }); Sample Data db.comparingTwoFieldsDemo.insertMany([ { ... Read More